An electrical switch having an obliquely orientated roller contact

ABSTRACT

An electrical switch comprises a base, a cover extending over the base and a rotor mounted between the base and the cover for angular movement relative thereto. A conductive roller is carried by the rotor and defines the movable contact of the switch, resilient means urging the roller into contact with the base. A pair of fixed contacts are carried by the base and are engageable by the roller in a predetermined angular position of the roller. The roller is carried by the rotor so that the rotational axis of the roller is parallel with the base but is inclined at an angle to an imaginary line joining the axis of movement of the rotor to the center of gravity of the roller, whereby during angular movement of the roller over the pair of fixed contacts the surface of the roller undergoes sliding movement as well as rotational movement relative to the fixed contacts and so provides a cleaning action to the contacts.

. [73] Assignee: Joseph Lucas (Industries) Limited,

United States atent 1 91 1111 3,715,547

Tregurtha 1 Feb. 6, 1973 541 ELECTRICAL SWITCH HAVING AN FOREIGN PATENTS OR APPLICATIONS OBLIQUELY ORIENTATED ROLLER 767,769 9/1967 Canada ..200/61.28

[75] Inventor: Steven John Tregurtha, Oswaldtwis- Primary ExaminerRobert K. Schaefer tle, England Assistant Examiner-M. Ginsburg AttorneyHolman & Stern Birmingham, England [57] ABSTRACT [22] plied: March 1971 An electrical switch comprises a base, a cover extend- [21] Appl. N0.: 129,454 ing over the base and a rotor mounted between the base and the cover for angular movement relative thereto. A conductive roller is carried by the rotor and [30] Forelgn Apphcatlon Priority Data defines the movable contact of the switch, resilient May 16, 1970 Great Britain ..23,833/70 means urging the roller into contact with the base. A

pair of fixed contacts are carried by the base and are [52] U.S. Cl. ..200/166 BB, 200/11 1,200/6127 engageable by the roller in a predetermined angular [51] Int. Cl. ..H01h 9/00 position of the roller. The roller is carried by the rotor [58] Field of Search ..200/6l .27-61.38, so that the rotational axis of the roller is parallel with 200/166 BB, 166 BH, 11 J the base but is inclined at an angle to an imaginary line joining the axis of movement of the rotor to the [56] References Cited center of gravity of the roller, whereby during angular movement of the roller over the air of fixed contacts UNITED STATES PATENTS the surface of the roller undergo es sliding movement 2,430,215 11/1947 Doucette ..200 11 K as well, as rotational ent relative to the fixed 2,629,787 2/ 1953 contacts and so provides a cleaning action to the con- 3,175,052 3/1965 tactsl 3,534,189 10/1970 Wilkinson ..200/61.34 3,585,544 6/1971 Cleaveland et a1. ..'....200/l1 A X 2 Claims, 4 Drawing Figures PATENTEDFEB ems 3.715547 SHEET 10F 2 INVENTOR ATTORNEYS PATENTEDFEB BIHH 3.715541 SHEET 20F 2 l NVE NTOR C A'TTRNEYS ELECTRllCAlL SWITCH HAVING AN OBLIQUELY ORllENTATlED ROLLER CONTACT This invention relates to electrical switches.

An electrical switch, according to the invention, comprises a base, a cover extending over the base, a rotor mounted between the base and the cover for angular movement relative thereto, a conductive roller carried by the rotor and defining the movable contact of the switch, resilient means urging said roller into contact with the base, and a pair of fixed contacts carried by the base and engageable by said roller in a predetermined angular position of the rotor, said roller being carried by the rotor so that the rotational axis of the roller is parallel with the base but is inclined at an angle to an imaginary line joining-the axis of movement of the rotor to the center of gravity of the roller, whereby during angular movement of the roller over said pair of fixed contacts the surface of the roller undergoes sliding movement as well as rotational movement relative to the fixed contacts and so provides a cleaning action to the contacts.

Preferably, a further pair of fixed contacts are carried by the base and are engageable by said roller in a further predetermined angular position of the rotor, said pair of fixed contacts and said further pair of fixed contacts being so positioned on the base that the portions of the surface of the roller engaged by the pair of fixed contacts respectively in said predetermined angu lar position of the rotor are axially spaced from the portions of the surface of the roller engaged by the further pair of fixed contacts respectively in said further predetermined angular position of the rotor.

In the accompanying drawings:

FIG. l'is a sectional side view of a switch according to one example of the invention, and

FIG. 2 is a plan view of the switch shown in FIG. 1 with the cover plate removed for the sake of clarity,

FIG. 3 is a diagrammatic illustration of the operation of the switch shown in FIG. 1, and

FIG. 4 is a diagrammatic illustration of the operation of a switch according to a second example of the inventron.

Referring to the drawings, the switch includes a moulded synthetic resin base 11 and a cover plate 12 supported above the base 11. A rotor 13, formed from a phenolic material, is positioned between the cover plate 12 and the base 11 and is formed with an integral pivot post 14 which is received in an aperture in the cover plate 12 so as to journal the rotor 13 for angular movement relative to the base 11 and the cover plate 12 about the pivot post 14. Mounted in respective bores 15 in the rotor 13 are a pair of conductive rollers 16, each of the rollers 16 being urged into engagement with the base 11 by a helical compression spring 17 received in the respective bore 15. The rollers 16 each define a movable contact of the switch and a pair of contact blades 18,19 received in respective apertures (not shown) in the base 11 are positioned adjacent each of the rollers 16 so as to be engageable by their respective rollers during angular movement of the rotor 13. The pairs of contact blades 18,19 define the fixed contacts of the switch and are arranged so that the rotor 13 is movable between an inoperative position in which no circuits are made, a first operative position in which one of the rollers 16 bridges one pair of fixed contacts 18 19, and a second operative position in which the other roller 16 bridges the other pair of fixed contacts 18, 19'. Detent means (not shown) are provided for releasably retaining the rotor in its inoperative position and the first and second operative positions. Further the rotor 13 supports an operating lever 21 which at one end extends from the rotor 13, the portion of the lever 21 extending from the rotor 13 being gripped, in use, to impart movement to the rotor.

The switch described above is a direction indicator switch and the base 11 and the cover plate 12 are provided with aligned holes 22,23 respectively so that the switch can be mounted on the steering column of a road vehicle; When the switch is mounted on the road vehicle, a bearing bush 24 mounted on the steering column for rotation therewith is received in the holes 23, in the cover plate l2,the bush 24 being provided on its outside surface with an integral striker 25. Further the rotor 13 carries a pair of flexible cancelling arms 26 arranged on opposite sides respectively of the post 14 so that, in use, when the rotor 13 is moved into an operative position one of the cancelling arms 26 is moved into the path of movement of the striker 25. Each of the arms 26 is arranged so that, in use, when engaged by the striker 25 during movement of the striker in one angular direction with respect to the arm, the arm is flexed laterally to allow the striker to move past the arm. However, when the striker is moving in the opposite angular direction with respect to the arm lateral flexing of the arm is resisted by an abutment 26a on the rotor 13 so that the striker applies a force to the rotor to return the rotor from its respective operative position back to its inoperative position, unless the rotor 13 is held, whereby the arm can bend along its length to allow the striker to move past the arm. It is of course to be appreciated that the arrangement of the arms 26 described above is known for direction indicator switches. in addition, the switch includes a further set of electrical contacts 27, the operating lever 21 being capable of angular movement about an axis at right anglesto the rotational axis of the rotor 13 so as to operate respective pairs of the further set of contacts 27 which would normally control the headlamps of the vehicle.

Referring now in particular to FIG. 3, the rollers 16 are so positioned in their respective bores 15 in the rotor 13 that the rotational axis of each roller 16, although parallel to the base 11, is inclined at an angle to an imaginary line joining the axis of angular movement of the rotor 13 generally shown at 28, and the center of gravity of the respective roller 16, generally shown at 29. Thus during angular movement of the rotor relative to the base 11 the frictional force between each roller 16 and the base 11 does not act directly at right angles to the axis of rotation of the roller. Further the frictional force between each roller and the base is arranged to be so inclined to the axis of rotation of the respective roller that during angular movement of the rotor relative to the base the surface of the roller not only rotates but also slides with respect to the base. In this way as each roller 16 is moved into and out of bridging engagement with its respective pair of contact blades 18,19 a rubbing action is applied to the surfaces of the contact blades by the roller 16 so that the surfaces of the contacts and the roller are clean during operating of the switch.

In a switch according to a second example of the invention, operation of the switch being illustrated by FIG. 4, a roller 31 is carried by an insulating rotor (not shown) and, as in the previous example, is arranged so that the rotational axis of. the roller is inclined at an angle to an imaginary line joining the axis of angular movement of the rotor, generally shown at 32, and the center of gravity of the roller, generally shown at 33. During angular movement of the rotor, the roller 31 is arranged to engage a first pair of contact pins 34 in a first angular position of the rotor and engage a second pair of contact pins 35 in a second angular position of the rotor. As before, as the roller 31 is moved into and out of engagement with the pairs of contact pins, a rubbing action is applied to the contact pins and the surface of the roller 31, so that the contact pins and the roller are cleaned during the operation of the switch. Moreover, the contact pins 34,35 are arranged so that the portions of the surface of the rollers 31 which engage the contact pins 34 in the first angular position of the rotor, and which are shown at 36, are axially separated from the portions of the roller 31 which engage the contact pins 35 in the second angular position of the rotor, and which are shown at 37. In this way, since different areas of the movable contacts are engaging the different sets of contact pins, it is possible to reduce the tendency for one particular area of the movable contact to be burnt away because of sparking in use. In the particular example shown this is effected by positioning each of the contact pins 34 near the axis of movement of the rotor 31 than their respective contact pins 35, while keeping the separation between the contact pins in each pair of contact pins 34,35 the same. However, the effect can also be achieved by varying the separation between the contact pins in each pair of contact pins. Further, it is to be appreciated that contact blades could be used to replace the contact pins in the arrangement described in this second example of the invention.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electrical switch comprising a base, a cover extending over the base, a rotor mounted between the base and the cover, for angular movement relative thereto, a conductive roller mounted in a bore in the rotor and defining the movable contact of the switch, resilient spring means also disposed in said bore for urging said roller into contact with the base, and a pair of fixed contacts carried by the base and engageable by said roller in a predetermined angular position of the rotor, said bore in the rotor and said roller mounted therein being positioned and aligned so that the rotational axis of the roller is parallel with the base but is inclined at an angle to an imaginary line joining the axis of movement of the rotor to the center of gravity of the roller, whereby during angular movement of the roller over said pair of fixed contacts the surface of the roller undergoes sliding movement as well as rotational movement relative to the fixed contacts and so provides a cleaning action to the contacts.

2. An electrical switch comprising a base, a cover extending over the base, a rotor mounted between the base and the cover for angular movement relative thereto, a conductive roller carried by the rotor and defining the moveable contact of the switch, resilient means ur ing said roller into contact with the base, and a pair of lxed contacts carried by the base and engageable by said roller in a predetermined angular position of the rotor, said roller being carried by the rotor so that the rotational axis of the roller is parallel with the base but is inclined at an angle to an imaginary line joining the axis of movement of the rotor to the center of gravity of the roller, whereby during angular movement of the roller over said pair of fixed contacts the surface of the roller undergoes sliding movement as well as rotational movement relative to the fixed contacts and so provides a cleaning action to the contacts, and wherein a further pair of fixed contacts are carried by the base and are engageable by said roller in a further predetermined angular position of the rotor, said pair of fixed contacts and said further pair of fixed contacts being so positioned on the base that the portions of the surface of the roller engaged by the pair of fixed contacts respectively in said predetermined angular position of the rotor are axially spaced from the portions of the surface of the roller engaged by the further pair of fixed contacts respectively in said further predetermined angular position of the rotor. 

1. An electrical switch comprising a base, a cover extending over the base, a rotor mounted between the base and the cover for angular movement relative thereto, a conductive roller mounted in a bore in the rotor and defining the movable contact of the switch, resilient spring means also disposed in said bore for urging said roller into contact with the base, and a pair of fixed contacts carried by the base and engageable by said roller in a predetermined angular position of the rotor, said bore in the rotor and said roller mounted therein being positioned and aligned so that the rotational axis of the roller is parallel with the base but is inclined at an angle to an imaginary line joining the axis of movement of the rotor to the center of gravity of the roller, whereby during angular movement of the roller over said pair of fixed contacts the surface of the roller undergoes sliding movement as well as rotational movement relative to the fixed contacts and so provides a cleaning action to the contacts.
 1. An electrical switch comprising a base, a cover extending over the base, a rotor mounted between the base and the cover for angular movement relative thereto, a conductive roller mounted in a bore in the rotor and defining the movable contact of the switch, resilient spring means also disposed in said bore for urging said roller into contact with the base, and a pair of fixed contacts carried by the base and engageable by said roller in a predetermined angular position of the rotor, said bore in the rotor and said roller mounted therein being positioned and aligned so that the rotational axis of the roller is parallel with the base but is inclined at an angle to an imaginary line joining the axis of movement of the rotor to the center of gravity of the roller, whereby during angular movement of the roller over said pair of fixed contacts the surface of the roller undergoes sliding movement as well as rotational movement relative to the fixed contacts and so provides a cleaning action to the contacts. 